To learn more, start your googling with these keywords: Direct transmission: occurs when a pathogen is transmitted to a new host by physical or close contact Virulence: the degree of damage a pathogen causes its host _________________________________________

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de Roode, J.C., Yates, A.J., & Altizer, S. (2008). Virulence-transmission trade-offs and population divergence in virulence in a naturally occurring butterfly parasite. Proceedings of the National Academy of Science 105: 7489-7494